Hydraulic couplers for quickly connecting and disconnecting construction attachments from excavating equipment are well known. A major problem with existing couplers is that a failure of the primary locking force, typically a hydraulic failure, can cause the attachment to swing or even completely detach from the coupler posing a safety hazard. Another problem is operator misuse or accidental operation of the coupler again leading to a safety hazard. Hydraulic failure can be particularly problematic in couplers that can accommodate attachments with different pin spacings since, depending on the pin spacing, there can be more scope for movement of pins with respect to the coupler in the event of a failure and this can increase the likelihood that the pins can escape.
It would be desirable to provide an improved coupler that is capable of retaining both pins of an attachment in the event of hydraulic failure as well as accommodating attachments with different pin spacings.